SU703604A1 - Correcting additive to electrolyte for production of aluminium - Google Patents

Description

-. -I

This invention relates to the field of light metal electrometallurgy, in particular, to the electrolyte technology of the aluminum production process.

At present, various additives of oxides and salts are introduced into the electrolyte to improve the technical and economic indicators of the process of electrolytic production of aluminum. Moreover, each additive itself can affect the individual physicochemical properties of the electrolyte both positively and negatively. For example, in the electric production of aluminum, the additive of millshp has a positive effect, lowering the temperature of the onset of crystallization and the viscosity of the electrolyte. At the same time, the electrical conductivity of the electrolyte decreases. Therefore, the value of the additive is determined by its complex effect on the properties of the electrolyte. In this connection, in modern practice, an adjustment of the composition of the electrolyte with mixed additives is used, which had more favorable properties: than the kg-component of each individual.

A known corrective electrolyte additive for the production of aluminum, including calcium and magnesium fluorides, sodium chloride and lithium hydroxide or lithium carbonate 1.

Its disadvantages are low efficiency (only partial complex effects on the properties of the electrolyte with separate addition of the components of the additive to the melt), high consumption of fluoride salts in the fluorination of lithium compounds, as well as the high cost and scarcity of lithium salts.

Known corrected. electrolyte additive to produce apyumin, which is a mixture composed of chloride oxides 12. This additive allows to improve the technological performance of the electrolysis process due to the complex effect on the properties of the electrolyte, reducing the cost of raw materials and saving fluoride salts. However, with a general economy. fluoride salts by reducing the electrolyte distemper and increasing its consumption, a large amount of fluorine is consumed for the fluorides and implants contained in the additive. This leads

to a violation of the electrolyte composition, an increase in the cryolite ratio, the need for additional adjustments of the composition of the electrolyte with aluminum fluoride, which has a long history).

The purpose of the present invention is to improve the technical and economic performance of the electrolyzer process by stabilizing the electrolyte and saving fluoride.

salts in the case of complex electrolyte properties.

The goal is achieved by the fact that dobicus contains a calcium chloride and magnesium fluoride With the following components,% by weight:

Sodium chloride 10-22

 HAYRSH 1 SH18

Calcium Chloride 2 - 6

Chloride and magnesium fluoride at ratios from 1: 1 to 3: 1. The remaining Corrective additive significantly improves the physicochemical properties of the electrolyte. Moreover, the influence of the components of the shichs complement each other. For example, the caustic metal chlorides compensate for the negative effect of magnesium chloride on the electrical conduction of the melt. The lower limits of ISLAYER STORES are as follows. The upper limits of the charge components are determined by the negative influence of each of the components on the properties of the electrolyte. Reducing the lower limit is inexpedient due to insufficient supply, and increasing the value of the game effect with each other component of the charge on the electrolyte properties.

while limiting the total number of additives in the electrolyte (not more.). The absence of oxides and the presence of fluorides in the container allow us to avoid the consumption of fluorine for the fluorination of oxides and the additional adjustment of the composition of the electrolyte with aluminum fluoride.

The ratio between mother chloride and fluoride from 1: 1 to 3: 1 is determined by the composition of the electrolyte, in particular, its crystallite ratio. The larger the latter, the lower the orbital density between chloride and magnesium fluoride., The additive is applied as follows: The MULTIPLE SAFETY is composed of a mixture of the above ratios. Next, the mixture is loaded into electrolytic cells on cryo-Alumina crust. After some heating, the Schicht conducts a general or local treatment of the electrolyzer and immersing the melt into the melt. . .,. .. IB quality blends can be applied to high purity mixtures of fluoride and chloride salts of magnesium, potassium and sodium, obtained in the production of magnesium-carbonic ligature by the magnesium-thermal method, which now mostly go to the dump, despite the presence of valuable composites. In this case, it is possible to adjust the electrolyte using briquettes.

Example. Additives have been prepared containing the above components in different ratios. For comparison, an additive was also prepared, the composition of which is indicated in the prototype. These additives were introduced into the electrolyte to allow aluminum to be obtained by electrolysis of the cryolite – ground-earth melt. The table shows the results of experiments.

18 21 left

10 18 .2 15 13 4 22-86

stop 1: 1 left 2: 1 left 3: 1 5703 As can be seen from the table, the electrolyte sponge is stable, which has a positive effect on the electrolyte process., Fo rumula and 3 about a b e n n Correcting additive to the electrolyte To obtain aluminum containing chloride sodium, potassium chloride, and magnesium chloride, which means that, in order to iniBbnife tehikoeconomic bbl electrolyte products, it additionally contains the electrolyte composition and savings of fluoride salts in order to ensure electrolyte properties on the electrolyte, and calcium magnesium chloride 046 next Compatibility of components,% by mass Sodium chloride 10-22 Potassium chloride 8-18 5 Chloride salt 2-6 Magnesium chloride and magnesium fluoride. . ratios from 1: 1 to 3: 1 Else, U Sources of information taken into account during the examination 1- USSR author's testimony. N 458626, cl. C 25 C 3/06, 1965. 5 2. USSR copyright certificate in application number 2449026/02, cl. C 25 C 3/1 AND, 01.25.77.